Document stacker system

ABSTRACT

The specification discloses a document stacker system which may accommodate various sizes of documents which flow at a variable frequency. The stacker system includes a rest station which includes a set of fingers upstanding in the path of travel of incoming documents in order to arrest the movement of the documents. Springs urge the documents downward to engage the fingers. Cans are disposed between the fingers to periodically raise the end of the document arrested by the fingers above the fingers. A pair of resilient rollers are synchronized with the cams to contact the top and bottom surfaces of the document raised by the cams. A transport then receives the document from the pair of rollers for delivery to various stacker receptacles. Each stacker receptacle includes a paddle which is movable vertically within the receptacle for supporting a document stack. A motor is operable to drive the paddle to a desired level within a receptacle in accordance with the sensed height of the document stack within the receptacle. A one-way clutch prevents downward movement of the paddle unless positive drive is provided from the motor, such that the operation of the paddle is substantially independent of the weight of the documents thereupon.

United States Patent 1 Monday 1 June 5,1973

[54] DOCUMENT STACKER SYSTEM [75] Inventor: William C. Monday, Garland,Tex.

[73] Assignee: Recognitioh Equipment, Incorporated, Irving, Tex.

[22] Filed: July 2, 1971 [21] App1.No.: 159,216

[52] US. Cl. ..27l/64, 271/53, 271/88 [51] Int. Cl. ..B65h 29/60 [58]Field of Search ..271/53, 60, 64, 86, 271/88, 35; 214/6 DK [56] 7References Cited UNITED STATES PATENTS 3,086,772 4/1963 Vogel ..27l/6O X3,633,903 1/1972 Foster ..27l/88 X Primary Examiner-Richard E. AegerterAssistant ExaminerJohnny D. Cherry Attorney-Richards, Harris & Hubbard[57] ABSTRACT The specification discloses a document stacker systemwhich may accommodate various sizes of documents which flow at avariable frequency. The stacker system includes a rest station whichincludes a set of fingers upstanding in the path of travel of incomingdocuments in order to arrest the movement of the documents. Springs urgethe documents downward to engage the fingers. Cans are disposed betweenthe fingers to periodically raise the end of the document arrested bythe fingers above the fingers. A pair of resilient rollers aresynchronized with the cams to contact the top and bottom surfaces of thedocument raised by the cams. A transport then receives the document fromthe pair of rollers for delivery to various stacker receptacles. Eachstacker receptacle includes a paddle which is movable vertically withinthe receptacle for supporting a document stack. A motor is operable todrive the paddle to a desired level within a receptacle in accordancewith the sensed height of the document stack within the receptacle. Aone-way clutch prevents downward movement of the paddle unless positivedrive is provided from the motor, such that the operation of the paddleis substantially independent of the weight of the documents thereupon.

16 Claims, 13 Drawing Figures PAIENTEDJuu SISTS 3.737.160

SHEET 10F 7 INVENTORZ WILL IAM C. MONDAY ATTORNEYS PATENTEDJUH 5 I915SHEET 2 BF 7 INVENTOR. WILLIAM C. MONDAY ATTORNEYS PATENTED H 5 I97SHEET 3 [IF 7 INVENTOR: WILLIAM C. MONDAY ATTORNEYS PATENTEUJUH 5l973SHEET 5 OF 7 FIG. 6

INVENTOR: WILLIAM C. MONDAY ATTORNEYS PATENIEDJUH 5|975 3.737.160 SHEETGDP 7 FIG. 7

g INVENTOR:

, WILLIAM C. MONDAY ATTORNEYS PATENTEDJUN 51975 SHEET 7 BF 7 FIG. 8

INVENTORZ WILL IAM C. MONDAY ATTOR NE YS 1 DOCUMENT STACKER SYSTEM FIELDOF THE INVENTION THE PRIOR ART Various document processing systems, andin particular automatic optical character recognition systems, have beendeveloped to process documents of varying size and paper character. Forexample, 8-% X 11 inch typewritten sheets may comprise input data to acharacter recognition system in which each document is to be read lineby line, in which case the document feed rate through the system wouldbe relatively slow. However, the document feed rate of a characterrecognition system would be relatively fast when the input datacomprises credit card documents wherein a single line only is to beread. Document stacking systems for character recognition systems haveheretofore been provided which have varied widely depending upon thedesired application, but which have often not been satisfactory withrespect to flexibility in acceptance of various document sizes and inacceptance of document feed rates which widely vary.

The present invention is directed particularly to a document stackercapable of accommodating documents of wide variance in size and flowrates, and at the same time capable of handling relatively stiffcardboard documents as well as more flexible sheet materials.

SUMMARY OF THE INVENTION In accordance with the present invention,capability for handling and stacking varied documents at varied demandrates are provided. A transport moves documents along a path of travel.A plurality of spaced apart abutment fingers are upstanding in the pathof travel of the documents for arresting the movement of the documentsat a predetermined location. Cams are disposed between ones of theabutment fingers for periodically raising the end of a document abovethe abutment fingers. Roller members are synchronized with the cams forcontacting the raised end of the document and for feeding the documentto the next station fol-stacking.

In accordance with another aspect of the invention, a document transportis provided for delivery of documents to a stacker, wherein thedocuments may vary in size and flow at a variable frequency. Thetransport includes an input surface having at least one moving beltalong which each document is fed. Air flow is directed upon the inputsurface to force each document against the belt to move the document atbelt speed. A set of fingers are upstanding in the path of travel of thedocuments fed from the belt. Springs urge the documents downwardly toengage the fingers. A pair of resilient rollers are adapted to contacttop and bottom surfaces of the document arrested by the fingers. Camsare synchronized with the pair or rollers to raise the end of thedocuments above the fingers. A transport receives the documents from thepair of rollers for delivery to the stacker.

In accordance with another aspect of the invention, a stacker system isprovided wherein documents of varying sizes may be accommodated. Atleast one stacking receptacle is provided for the documents and includesa paddle support which is movable vertically within the receptacle tosupport a document stack. A motor is operable to drive the paddlesupport to a desired level within the receptacle in accordance with theheight of the document stack. A constant force spring biases the paddlesupport in an upward position. A oneway drive prevents downward movementof the paddle support unless positive drive 'is provided from the motor.

DESCRIPTION OF THE DRAWINGS For a more complete understanding of thepresent application, and for other objects and advantages thereof,reference is now made to the following description taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a layout of an optical reading system including the documentstacker of the present invention;

FIG. 2 is a somewhat diagrammatic representation of a documenttransport, reading and stacker system;

FIG. 3 is a perspective view of the reststation for use with the presentstacker; 7

FIGS. 4a-c are side views of various positions of the rest station ofthe present invention;

FIG. 5 is a side view of the present stacker unit;

FIG. 6 is a top view of the present stacker unit;

FIG. 7 is another side view of the present stacker unit;

FIG. 8 is a top view of the one-way drive for use with the paddle drivesystem of the invention;

FIG. 9 is a partially sectioned view of the drive shown in FIG. 8;

FIG. 10 is a sectional view taken section lines 10-10 in FIG. 9; and

FIG. 11 is an end view of the splined shaft shown in FIG. 9.

The present document stacker system may be best understood by referenceto its relation to a complete document reading system. Referringto FIG.1, a page processor 10 is employed for the feeding, scanning andstacking of documents. The page processor comprises a feeder unit 11, atransport scanning unit 12 and a I one-way generally along the stackingunit 13 to which the present invention is directed. Peripheralequipment-to the system comprises a control console 14, an I/O unit 15,a peripheral control unit 16, a recognition unit 17 which includes logiccircuitry for the recognition of characters of fixed fonts as well ascharacters of handprint execution, a line printer 18 and a tapetransport unit 19.

The system shown in FIG. 1 has the capability of accepting 9 X 14 inchdocuments with single spaced full coverage of the document. The systemis capable of reading and completely transferring to storage, to lineprinter 18 or tape transport 19 all ofthe information on such documentsat rates of the order of about thirty pages per minute. On the otherhand, credit card type documents, wherein the reading is to beaccomplished on one or two lines only, can be processed by the presentsystem at the rate of up to 300 cards per minute. The system operates byplacing into a hopper in feeder 11 a stack of documents to be read,feeding the documents one at a time into the'tape transport and scanningunit 12, and then delivering the documents to the stacking unit 13wherein the stacking can be selectively dependent upon any codedinformation on the documents themselves.

In order to provide an understanding of the setting in which the presentinvention finds itself and the desirability for the unique capabilitiesof the stacker of the present invention, the line diagram of FIG. 2 willbe described.

Referring now to FIG. 2, a document feeder 11 has been illustrated ascomprising a tray in which a stack D of documents may be placed with thedocuments being oriented as to stand on the bottom edge thereof. Apaddle 31 is slidably mounted to move the documents forward against ashuttleplate unit 32. The paddle 31 is linked mechanically as by linkage33 to a chain 34 which is servo driven to maintain the documents in agiven density in the region of the face of the shuttleplate unit 32. Ashuttleplate 35 is reciprocated through a crank unit 36 on a shaft 37driven by a feeder motor 38 through a single revolution clutch 38a. Theshuttleplate 35 has a plurality of apertures formed through it. A vacuumis maintained in the apertures through a vacuum system connected to anexhaust pipe 39. By this means, individual documents are sequentiallyremoved from the stack D and are moved downwardly into engagement with aset of pinch rollers that are diagrammatically represented at 40.

The pinch rollers 40 direct each document into the document transportscanning unit 12 wherein the document is advanced by a belt that isdriven by a pair of servo motors 51 and 52 in response to a positionencoder 53 and a suitable control system. Documents are maintained incontact with the belt 50 by a series of rollers 54 as well as by jets ofair that are directed downwardly from parallel tubes 55 and 56positioned above and on opposite sides of the belt 50. In the region ofarc 60, the documents are drawn into a fixed position against a bedplateby a plurality of vacuum ports (not shown). Are 60 represents the scanlocation of documents traveling under the action of the belt 50, and thearrow 59 represents the direction of travel of the documents.

At the scan location, light from a high intensity lamp 62 passes througha lens system 63 onto an oscillating mirror 64 and is projected andfocused onto a scan point on are 60. The mirror 64 is mounted on a shaft65 that is driven by a servo motor 66 having a servo tachometer 67associated therewith and an encoder 68 responsive to the movement of theshaft 65. A scanning mirror 70 is mounted on the shaft 65 foroscillation with the mirror 64. Light reflected from the mirror 70passes through a lens system 71 onto a columnar retina 72. In oneembodiment of the system, the retina 72 is provided with ninety-sixactive cells and is operated such that characters viewed by the retinaas the light beam sweeps are 60 actually fall on or energize sixteencells for a normal character, i.e., a character of usual type printheight. The remainder of the cells of the retina are employed in thesystem for locating the next line to be scanned and for providingcontrol signals to the servo motors 51 and 52, whereby the document isproperly positioned for the initiation of the scan of the next line.

Once scanned, each document is fed to a rest station 13a at the input ofthe stacker unit 13. The movement of the document is arrested at therest station to permit the stacker unit to respond to controlinstructions. Then in accordance with such control instructions, thedocument is delivered, either to a selected one of three bins a, 80b,and 80c, or to a reject bin 80d. The

movement of documents in the stacker unit 13 is under the control ofstacker gates 81, 82 and 83, and spiral stacking wheels are employed todeliver documents to the selectable bins 80a, 80b, and 800.

In order to accommodate documents of different weights, a positivecontrol is provided through a stacker motor 86 operating throughclutches 88a, 88b, and 88c to maintain the top of the stack of thedocuments on each of the paddles 80ac, respectively, in a predeterminedrelation to the periphery of the spiral stacking wheels. In each bin,the document level is sensed by photocells to control the respectiveclutches 88a-c.

Within this environment, the document stacker 13 of the presentinvention is called upon to provide reliable feed and stacking ofdocuments to the system in each of the many various conditions that maybe prescribed by a user. The system of FIGS. 1 and 2 thus may operate ina wide variety of conditions and thus may be termed a universal documentreader, being limited only by the maximum size of documents that can beaccommodated in the document transport and stacking systerns.

Photoelectric sensors 89, not shown, are disposed adjacent the paddles80ac and control the operation of the stacker motor 86. The paddles80a-c are respectively slidably mounted upon shafts 9011-0 and are movedalong the shafts 90a-c by operation of suitable belts or chains 92a-c.Chains 92ac are reaved over pulleys 94a-c and 96a-c. Each of the chains92a-c is respectively coupled through negators spring 98a-c, with theend of each of the constant force springs being connected to a rigidframe. Operation of the stacker motor 86 may then move the chains 92acto move the paddles 80a'c vertically along the shafts 9011-0, in orderto maintain the stack of documents thereon in a predeterminedrelationship to stacking wheels 100a-c. Wheels 100a-c serve todecelerate and stack documents fed from the rest station 13a. Forfurther description of the control of deflecting blades for selectivestacking of documents with a plurality of pockets, reference is made toU. S. Pat. No. 3,460,673, issued on Aug. 12, 1969, to the presentassignee.

FIG. 3 illustrates in perspective detail the construction of the reststation 130. A plate supports a first set of abutment fingers I 12 whichinclude a plurality of spaced apart fingers with abutment portions 114upstanding in the path of travel of documents fed to the system. Plate110 also supports a second set of abutment fingers 116 which comprises aplurality of spaced apart fingers-with abutment portions 118 alsoupstanding in the path of travel of the documents. The set of abutmentfingers 112 in the preferred embodiment comprises a larger number ofspaced apart fingers than does the set of abutment fingers 116. Thenumber and spacing of abutment members on the two sets of fingersdiffers to prevent canted documents from sticking or otherwise lodgingbetween the fingers. The belt, not shown, which delivers the documentsto the rest station 13a are slightly canted a few degrees to providepositive control of the documents fed to the station.

A support 120 is attached to a pair of spring supports 122 and 124.Spring support 122 supports a plurality of resilient spring fingers 126which tend to prevent documents from slipping over the upstandingabutment portions 114. Likewise, a set of resilient spring fingers 128is connected to support 124 and exerts a downward bias to aid inpreventing documents from slipping over the upstanding abutment portions118. A shaft 130 supports a first set of spaced apart cams 132 and asecond set of spaced apart cams 134. Cams 132 are spaced between each ofthe abutment fingers 112, while cams 134 are disposed between each ofthe abutment fingers 116.

Shaft 130 also supports a pair of spaced apart pincher rollers 136 and138. A belt 140 rotates the pincher rollers and the cams 132 and 134 insynchronism. An upper pair of pincher rollers 142 and 144 are mountedfor rotation about a shaft 146. Rotation of the rollers 142 and 144operates a drive belt 148. The pincher rollers 136, 138, 142 and 144include raised portions which are adapted to engage upper and lowerportions of a document which have been raised above the upstandingabutment portions 114 and 118 by the cams 132 and 134. The pincherrollers then move the document to a stacker unit for stacking upon aselected one of the paddles 80a-c.

FIGS. 4a-c best illustrate the operation of the rest station 130. Asshown in FIG. 4a, a document D is transported by suitable belts in themanner previously described until the movement of the document isarrested by the upstanding abutment portions 114. The stopping of themovement of the document D enables the control operations of the stackerto be synchronized for stacking of documents of various sizes and flowrates. In the position illustrated in FIG. 4a, the spring fingers 126urge document D downwardly against the fingers 112.

As shown in FIG. 4b, cams 132 rotate between the fingers 112 and comeinto contact with the document D in such a manner as to raise the edgeof the document D up above the abutment portions 114. As best shown inFIG. 4c, the projecting portions of the pincher rollers 138 and 144 thenengage upper and lower portions of the document D and move the documentwith some force to the selected stacker bin in the direction of thearrow 149.

Referring to FIG. 5, a side view of the stacker unit 13 is illustrated.The documents are fed from left to right, and initially come to rest atthe rest station 13a. Pressurized air is supplied via an air supply pipe150 through suitable apertures in order to apply pressurized airdownwardly upon the documents. A vacuum is also applied via members, notshown, to the underside of the documents in order to hold the documentsfirmly against the transport belt. The documents are brought to rest atthe rest station 13a in the manner previously described and then fed tothe stacker 13 for reception by a selected one of the stacker wheels100a-c.

The stacker wheels each comprise a plurality of spaced apart spiralelements such that a document is received between the elements andgently moved downwardly for stacking upon one of the paddles 80a-c. Aspreviously described, the paddles 80a-c are respectively mounted forvertical movement along the shafts 90a-c. Pressurized air is appliedthrough vents l52a c in order to fluff up the documents stacked upon thepaddles. Belt 148 is driven by the stacker motor in order to rotate thepincher rollers in the manner previously described. Suitably drivenbelts deliver the documents to the one of the stacker wheels 100a-cwhich has been selected by control of the stacker blades 82 and 84 aspreviously described.

FIG. 6 illustrates in detail the top view of the stacker unit 13.Pressurized air is applied through the air inlet pipe and is applieddownwardly through air nozzles and air pipes in order to force thedocuments against the transportation belts. A guide member 162 serves toguide the documents into place at the rest station 13a. Support 122supports the first set of spring fingers 126, while support 124 supportsthe second set of spring fingers 128 in the manner previously described.The belt 148 is driven by the pincher rollers 144 and 142 as previouslydescribed. A motor, not shown, rotates a belt 164 which rotates a shaft166 which provides rotating motion to the pincher rollers. A brushbracket 168 supports a brush and roller 170 which extends intoengagement with the documents in order to positively feed the documentsthrough the pincher rollers.

The stacker paddle operation may be best understood by referring toFIGS. 6 and 7. As shown in FIG. 7, a stacker motor 86 is mounted on theside of the system and applies drive through a gear box 180. A toothedbelt 182 is driven from the gear box and drives toothed belts 184 and186. Drive from the motor 86 is also applied through a belt 188 whichapplies drive through a gear box 190 and through the clutch 88a foroperation of the chain 92a. Chain 92a operates the paddle 80a in themanner'shown in FIG. 2. The constant force spring 98a is connectedbetween the system frame and the chain 92a, as previously described. Ablower 192 supplies pressurized air for the air fluffer mechanism andalso for application to the documents and drive belts.

Drive is also applied through belt 184 to a toothed belt 194 whichapplies drive through a gear box 196 to the'clutch 88a. Drive isprovided through the clutch 88b to a chain 92b to move the paddle 80b aspreviously described. The constant force spring 98b is connected betweenthe system frame and chain 92b. Drive is applied through belt 186 to abelt 202 which provides drive through a gear box 204 to the clutch 88c.Drive is provided through the clutch 880 to the chain 920 for movementof the paddle 800. Spring 980 is connected between the chain 92c and thesystem frame.

Blower 200 supplies pressured air to the document feeder. Blower 208provides the vacuum for the feeder operation.

FIGS. 8-11 illustrate in greater detail the construction of the one-wayclutches 88a-c. Drive is transmitted through a gear box 190 to a shaft250 which extends into the end of a body 252. As best shown in FIGS. 8and 9, shaft 250 includes an outwardly projecting knob 254 which extendsthrough a slot 256 in the body 252. The slot 256 is canted so thatrotation of the shaft 250 will cause the body 252 to be moved withrespect to the longitudinal. axis of the shaft 250. A counterboredhousing 258 is connected to body 252 and includes a one-way clutch andbearing 260 which rotatably receives an end of a shaft 262. As shown inFIGS. 9 and 10, the counterbore portion of housing 258 includes aplurality of cylindrical holes 264 therein. The end of the shaft 262includes a plurality of projections 266 which are adapted to mate withthe holes 264 to act as a spline. A pulley 280 is mounted on the end ofshaft 262 and may be operated to rotate the chain 92a.

In operation of the one-way clutch mechanism, if the paddle 80a isunloaded, the spring 98a exerts an upward force on the tooth belt 92a tomaintain the paddle 80a at its upper position. If a relatively lightstack of documents is provided on the paddle 80a and the photoelectricsensing device determines that the height of the stack is excessive,motor 86 is energized and the shaft 250 is rotated. The knob 254 rollsalong the slot 256 and earns the body 252 into contact with theprojections 266 of shaft 262. Shaft 262 is then rotated in order to movethe chain 92a in order to move paddle 80a downward into the desiredposition.

If an extremely heavy load is upon the paddle 80a, the weight of thedocument stack tends to rotate the pulley 280 and the shaft 262 even ifthe motor 86 has not been energized. A slight rotation on the shaft 262,however, causes the projections 266 to become disengaged from the holes264. Substantial downward movement of the paddle 80a then is preventedby the oneway clutch 260. When the motor 86 is energized, the shaft 250cams the housing 252 into engagement with the end of the projections 266on shaft 262 in order to positively drive the shaft 262. Thus, it willbe seen that the one-way clutch of the invention enables heavy documentloads to be held back until the proper document stack height is reached,and yet enables the paddle to be driven down under relatively lightloads of documents.

The present stacker is thus capable of handling documents ranging from arelatively small size, in the range of 3- /1 inches by 4% inches, tolarger sizes of up to 9 inches by 14 inches, with a minimum of requiredmachine setting changes. The present stacker accepts documents ofvarying sizes from a transport at random and at varying speeds, withouta required direct connection with an optical reader system. The presentconstant speed stacker, in conjunction with the rest station asdescribed, enables design simplicity while providing excellent stackingcharacteristics for documents of varying sizes and at varying feedrates. The present stacker paddle configuration enables positive controlof a document stack, regardless of the document stack weight.

Whereas the present invention has been described with respect tospecific embodiments thereof, it will be understood that various changesand modifications will be suggested to one skilled in the art, and it isintended to encompass such changes and modifications as fall within thescope of the appended claims.

What is claimed is:

1. A document transport system comprising:

means for moving documents along a path of travel,

a plurality of spaced apart abutment members upstanding in the path oftravel for arresting the movement of the documents at a predeterminedlocation,

cams disposed between said abutment members for periodically raising theend of a document above said abutment members, and

upper and lower resilient roller members synchronized with said cams andhaving mating raised portions for contacting the raised end of thedocument and for feeding the document to the next station.

2. The transport system of claim 1 wherein said abutment memberscomprise fingers extending generally parallel to the path of travel ofthe documents and including abutment end portions upstanding in the pathof travel.

3. The transport system of claim 2 wherein said cams rotate between saidfingers and include cam portions which periodically move above saidabutment end portions.

4. The transport system of claim 1 and further comprising: spring meansfor urging documents against said abutment members.

5. A document transport for delivery of documents to a stacker where thedocuments may vary in size and flow at a variable frequency whichcomprises:

an input surface having at least one moving belt along which eachdocument is fed,

means to direct air flow upon said input surface to force each documentagainst said belt to move the document at belt speed,

a set of fingers upstanding in the path of travel of documents fed fromsaid belt,

springs for urging documents downward to engage said fingers,

a pair of resilient roller means adapted to contact top and bottomsurfaces of the document arrested by said fingers,

cam means synchronized with said pair of roller means to raise the endof the document above said fingers, and

transport means to receive documents from said pair of roller means fordelivery to said stacker.

6. The document transport of claim 5 wherein said fingers are positionedin two spaced apart groups, said roller meansbeing disposed between saidgroups.

7. The document transport of claim 6 wherein said cam means areinterposed between adjacent fingers ments from said transport means,

means for selectively directing documents into one of said receptacles,and means in said receptacles for maintaining the height of thedocuments stacked therein at a predetermined level.

10. The document transport of claim 9 wherein said means for maintainingthe height of documents comprises:

a support paddle for supporting a stack of documents,

means for sensing the level of the stack of documents on said supportpaddle, and

means for vertically moving said paddle in response to said sensingmeans.

11. The document transport of claim 10 wherein said moving meanscomprises:

motor driven belt means connected to said paddle,

and

an electrical clutch responsive to said sensing means for transmittingdrive to said belt means. 12. The document transport of claim 11 andfurther comprising:

constant force spring means attached to said belt means to exert anupward force-on said paddle,

one-way drive means including a splined shaft rotatably journaled in ahousing, said shaft operable to drive said belt means, and

an output shaft from said electric clutch connected to cam said housingto and from contact with the end of said splined shaft, whereby saidpaddle may be accurately driven to a desired level regardless of theweight of the stack of documents thereon.

13. In a stacker system wherein documents of varying sizes must beaccommodated, the combination comprising:

a stacking receptacle for said documents including a paddle supportwhich is movable vertically within said receptacle for supporting adocument stack,

motor means operable to drive said paddle support to a desired levelwithin said receptacle in accordance with the height of said documentstack,

spring means for biasing said paddle support in an upward direction, and

one-way clutch means interconnecting said motor means and said paddlesupport for preventing downward movement of said paddle support unlessdrive is provided from said motor means.

14. The combination of claim 13 wherein said oneway drive meanscomprises:

a drive shaft having a splined end and connected to drive said paddlesupport at the other end,

a housing for rotatably receiving said splined end of said drive shaft,said housing including a corresponding splined portion, and w an outputshaft from said motor means extending into said housing and including alateral cam projection extending through a canted groove within saidhousing, whereby said drive shaft is operable to move said paddlesupport downwardly only when said motor output shaft is rotated to camsaid housing such that said splined end is mated with said splinedportion of said housing.

15. The combination of claim 14 and further comprising:

a flexible drive linkage moved by rotation of said drive shaft to movesaid paddle support, said negator spring means connected to said drivelinkage for biasing said paddle support upwardly.

16. The combination of claim 13 and further comprising:

means for sensing the height of said document stack,

and

means operable by said sensing means for applying drive from said motormeans.

1. A document transport system comprising: means for moving documentsalong a path of travel, a plurality of spaced apart abutment membersupstanding in the path of travel for arresting the movement of thedocuments at a predetermined location, cams disposed between saidabutment members for periodically raising the end of a document abovesaid abutment members, and upper and lower resilient roller memberssynchronized with said cams and having mating raised portions forcontacting the raised end of the document and for feeding the documentto the next station.
 2. The transport system of claim 1 wherein saidabutment members comprise fingers extending generally parallel to thepath of travel of the documents and including abutment end portionsupstanding in the path of travel.
 3. The transport system of claim 2wherein said cams rotate between said fingers and include cam portionswhich periodically move above said abutment end portions.
 4. Thetransport system of claim 1 and further comprising: spring means forurging documents against said abutment members.
 5. A document transportfor delivery of documents to a stacker where the documents may vary insize and flow at a variable frequency which comprises: an input surfacehaving at least one moving belt along which each document is fed, meansto direct air flow upon said input surface to force each documentagainst said belt to move the document at belt speed, a set of fingersupstanding in the path of travel of documents fed from said belt,springs for urging documents downward to engage said fingers, a pair ofresilient roller means adapted to contact top and bottom surfaces of thedocument arrested by said fingers, cam means synchronized with said pairof roller means to raise the end of the document above said fingers, andtransport means to receive documents from said pair of roller means fordelivery to said stacker.
 6. The document transport of claim 5 whereinsaid fingers are positioned in two spaced apart groups, said rollermeans being disposed between said groups.
 7. The document transport ofclaim 6 wherein said cam means are interposed between adjacent fingersand are rotated at a constant speed.
 8. The document transport of claim5 wherein said roller means contacts the top and bottom surfaces of adocument only when said document is raised by said cam means.
 9. Thedocument transport of claim 5 and further comprising: a plurality ofstacking receptacles for receiving documents from said transport means,means for selectively directing documents into one of said receptacles,and means in said receptacles for maintaining the height of thedocuments stacked therein at a predetermined level.
 10. The documenttransport of claim 9 wherein said means for maintaining the height ofdocuments comprises: a support paddle for supporting a stack ofdocuments, means for sensing the level of the stack of documents on saidsupport paddle, and mEans for vertically moving said paddle in responseto said sensing means.
 11. The document transport of claim 10 whereinsaid moving means comprises: motor driven belt means connected to saidpaddle, and an electrical clutch responsive to said sensing means fortransmitting drive to said belt means.
 12. The document transport ofclaim 11 and further comprising: constant force spring means attached tosaid belt means to exert an upward force on said paddle, one-way drivemeans including a splined shaft rotatably journaled in a housing, saidshaft operable to drive said belt means, and an output shaft from saidelectric clutch connected to cam said housing to and from contact withthe end of said splined shaft, whereby said paddle may be accuratelydriven to a desired level regardless of the weight of the stack ofdocuments thereon.
 13. In a stacker system wherein documents of varyingsizes must be accommodated, the combination comprising: a stackingreceptacle for said documents including a paddle support which ismovable vertically within said receptacle for supporting a documentstack, motor means operable to drive said paddle support to a desiredlevel within said receptacle in accordance with the height of saiddocument stack, spring means for biasing said paddle support in anupward direction, and one-way clutch means interconnecting said motormeans and said paddle support for preventing downward movement of saidpaddle support unless drive is provided from said motor means.
 14. Thecombination of claim 13 wherein said one-way drive means comprises: adrive shaft having a splined end and connected to drive said paddlesupport at the other end, a housing for rotatably receiving said splinedend of said drive shaft, said housing including a corresponding splinedportion, and an output shaft from said motor means extending into saidhousing and including a lateral cam projection extending through acanted groove within said housing, whereby said drive shaft is operableto move said paddle support downwardly only when said motor output shaftis rotated to cam said housing such that said splined end is mated withsaid splined portion of said housing.
 15. The combination of claim 14and further comprising: a flexible drive linkage moved by rotation ofsaid drive shaft to move said paddle support, said negator spring meansconnected to said drive linkage for biasing said paddle supportupwardly.
 16. The combination of claim 13 and further comprising: meansfor sensing the height of said document stack, and means operable bysaid sensing means for applying drive from said motor means.